Composes a new email based on a given key.
Craft has four predefined email keys: account_activation, verify_new_email, forgot_password, and test_email.
Plugins can register additional email keys using the
registerEmailMessages hook, and
by providing the corresponding language strings.

Throws

Signature

Sends the given email message.
This method will log a message about the email being sent.
If $useFileTransport is true, it will save the email as a file under $fileTransportPath.
Otherwise, it will call sendMessage() to send the email to its recipient(s).
Child classes should implement sendMessage() with the actual email sending logic.